Former New York Mayor Michael Bloomberg said Wednesday that he has changed his voter registration to Democrat, suggesting he is inching closer to announcing a presidential run in 2020.

The 76-year-old billionaire has switched political parties several times in the last couple decades. He had been a longtime Democrat before registering in 2001 as a Republican ahead of his first New York mayoral run. In 2007, while still mayor, he abandoned the Republican Party and registered as a political independent.

Bloomberg announced his new political affiliation in an Instagram post, warning that Democrats are “so badly” needed to keep the government in check.

“At key points in U.S. history, one of the two parties has served as a bulwark against those who threaten our Constitution,” Bloomberg wrote. “Two years ago at the Democratic Convention, I warned of those threats.

“Today, I have re-registered as a Democrat – I had been a member for most of my life – because we need Democrats to provide the checks and balance our nation so badly needs,” he added.

Bloomberg’s new party affiliation will likely fuel further speculation about a 2020 presidential run. He told The New York Times last month he is actively considering opposing President Donald Trump in the next presidential election.

“It’s impossible to conceive that I could run as a Republican — things like choice, so many of the issues, I’m just way away from where the Republican Party is today,” he told the Times. “That’s not to say I’m with the Democratic Party on everything, but I don’t see how you could possibly run as a Republican. So if you ran, yeah, you’d have to run as a Democrat.”

Bloomberg, who served three terms as mayor, is the founder and owner of Bloomberg L.P., a global financial services and media corporation. He endorsed Hillary Clinton in the 2016 election and was a vocal critic of Trump.

“Truth be told, the richest thing about Donald Trump is his hypocrisy,” Bloomberg said in his speech at Democratic National Convention in July 2016.

The media mogul reportedly planned to spend $80 million of his personal fortune on the 2018 midterm elections to help Democrats gain control of the House of Representatives. He also has contributed heavily to environmental and gun-control initiatives.